Canterbury quake research aims to put building design on more solid ground

Canterbury University researchers investigating the impact of earthquakes on different soil types hope their findings could lay the groundwork for better buildings.

• First published on RNZ

Lead researcher Felipe Kuncar, a PhD candidate, said his team of ten was using data from Christchurch's network of 20 strong motion sensors (accelerometers) to analyse localised seismic activity and feed the data back to his ground-motion simulation model.

In the next few months the researchers plan to expand their analysis to include more than 50 of these instruments across New Zealand.

Kuncar said the group was working with other researchers internationally and hoped their technique could be used to improve the seismic resilience of buildings all over the world.

"If we want engineers to use this modelling technique, they need to have confidence in it.

"Simulations are very complex, so the important step is to validate the computer simulations with real-life observations."

Many Cantabrians witnessed first-hand how homes and buildings on softer soil were more affected by quakes than areas closer to the airport, where ground conditions were much more stable, he said.

In Wellington, following the Kaikōura earthquake, buildings on softer land, like those near the port, had more damage than those on more solid ground.

"The soil is a softer material than the rock beneath it, and as a result it tends to amplify the ground shaking.

"We can compare this with a plate of jelly. If you shake a plate of jelly, the movement will be more severe at the top of the jelly than on the plate itself," Kuncar said.

"The soil has a significant impact on how we feel the ground shaking during an earthquake.

"The building code currently incorporates the soil, but only in a simplistic way. We hope to improve this practice, and think these simulations will be the future of earthquake resilient design."

The project is co-funded by Toka Tū Ake EQC, which puts about $20 million a year into natural hazard risk and engineering-related research each year.

Its head of research Dr Natalie Balfou, said the soil modelling was "the next frontier of seismic hazard analysis".

"We know different soils respond differently in earthquakes.

"It's really exciting to be building this understanding about ground shaking at such a local level, it means we can plan and build smarter and be better prepared."